How do I eat just fat when eating to satiety?

If you have no available protein of carbohydrate grams left for the day you will have to find food that has calories only from fat. You could eat a small amount of coconut oil or butter – like a teaspoon full – and wait 15 minutes until your body has digested the additional energy and reassess if you are still hungry. We like to cook a bunch of bacon, put it in the fridge, and when hungry, spread some cream cheese on a slice of bacon and use it like a cracker. If you have protein grams available you could eat some salami or some kind of meat. If you have excess carbs available for the day you could eat fatty nuts like Macadamia nuts. Be careful, though. A small handful once or twice a day is advisable. Still, you should test your reaction to all variable foods.